BEIJING – China confirmed on Wednesday that an explosion at a petrochemical plant had caused “major pollution” of a river which has led authorities to shut off water supplies in one of its biggest cities for at least four days.

Residents of Harbin, capital of far northeastern Heilongjiang province, were jamming the airport and rail stations to get out, a witness said.

China&#039s State Environmental Protection Administration said that the Songhua River had suffered “major water pollution” after the Nov. 13 explosion at the plant upstream, the CCP mouthpiece, Xinhua news agency said.

Taps were turned off in Harbin at midnight on Tuesday after two days of panic buying of bottled water and food in a city where winter temperatures regularly drop below minus 20 Celsius.

The explosion happened in neighbouring Jilin province only a few hundred metres (yards) from the Songhua River, which supplies water to Harbin, a metropolitan area of nine million people. Five people were killed in the blast.

“Pollution is definite,” said a regional water official, who declined to give his name. “It has entered the Songhua River and has affected the banks and lower reaches.”

The Beijing Times newspaper said the pollutants in the partly frozen river included benzene, an industrial solvent and component of petrol.

An environmental official quoted by Xinhua said the polluted water was expected to reach the stretch of river where Harbin siphons off its drinking water on Wednesday evening and clear the city by Friday afternoon.

“Several major tributaries join the Songhua River on the downstream of Harbin,” the official said. “It will help to lessen the degree of pollution.”

Hospitals on Standby

The Songhua runs into Russia several hundred kilometres beyond Harbin. A Foreign Ministry spokesman said on Tuesday that China always took care of other countries&#039 border water interests.

One factory manager told Reuters: “Everyone wants to leave Harbin and it is very difficult to buy tickets, just like during the Lunar New Year holiday.

“All containers are being used to store water, including the bathtub. It will be okay for four days, but not longer than that.”

Fifteen hospitals were on standby to take in contamination victims, Xinhua news agency said.

A notice on the city government Web site saying supplies would resume in four days has been superseded by another saying a resumption date would be announced later.

“The new notice does not necessarily mean an extension,” a Harbin government spokesman told Reuters. “But we will make a decision after four days according to the water quality at that time.

“There is sufficient water. Residents have all stored a lot and we have been rushing in water from other places. We also have safe underground water.”

Prices of bottled water soared in recent days and state media said shops had been ordered to restore prices to normal to prevent panic buying.

U.S. beer-making giant Anheuser-Busch, which runs a brewery in Harbin, said it had not been affected because it uses well water.

Harbin, a frontier town founded in the late 19th century, is famed for its old Russian- and European-style architecture. Each January it attracts crowds of tourists for a spectacular ice sculpture display.

“They did not have enough preparation, otherwise they would not have needed to shut down the water completely,” said Fu Tao, director of the Water Policy Research Centre at Beijing&#039s Tsinghua University.